In recent years, various wireless communication networks are spreading rapidly in ordinary homes and companies. Particularly, not only voice streaming service of the portable IP phone or the like using a wireless LAN, but also image streaming service such as IPTV are also attracting attention lately.
In a communication system utilizing the wireless communication such as wireless LAN, the same electric wave arrives to a plurality of terminal units existing in a range to which the electric wave from the base station apparatus called an access point reaches. The base station apparatus controls so that the electric waves from the plurality of terminal units may not collide with each other using Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) to thereby share the communication bands among the plurality of terminal units and achieve the communication with the plurality of terminal units.
In the wireless LAN, a situation in accordance with the communication changes with time due to factors, such as an obstacle on a communication path, a distance between the base station apparatus and the terminal unit, and a new communication request from the terminal unit.
When the communication state between the base station apparatus and terminal unit gets worse, a link rate which is a bit rate between the base station apparatus and terminal unit is gradually reduced to thereby keep communication quality. In order to reduce the link rate, however, the base station apparatus needs to ensure sufficient communication bands for the communication with the terminal unit. Naturally when the sufficient communication bands may not be ensured for the communication with the other terminal units, the base station apparatus terminates the communication with this terminal unit.
In addition, since streaming service of media, such as voices, images, or the like is uniformly set to have priorities, the base station apparatus substantially allocates the communication bands in the order of arrival, and starts the wireless communications for a communication request of the streaming service.
A method of properly controlling the communication bands to be allocated for every session in the network where various communication services are provided is disclosed in Patent Document 1.
[Patent Document 1] Japanese Laid-Open Patent Publication No. 2006-237678